<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" lang="en">
	<head>
		<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
		<title></title>
		<script type="text/javascript">
			var a = 3;
			var b = 7;
//			++在前先自增再运算
//			var res = a*++b;

//			++在后先运算再自增
			var res = a*b++;
			document.write(res);
			document.write(b);
		</script>
	</head>
	<body>

	</body>
</html>
